Why are those things an incentive to work your butt off? I see why those would lead to you being happy at your job, but I don't really see why being happy at yo

Why are those things an incentive to work your butt off? I see why those would lead to you being happy at your job, but I don't really see why being happy at your job means you should work extra hard. Just curious, as it seems to me those are things which would make someone stay at their job for a long time but not necessarily work extra hard. After all, it's not like your not working extra hard would lead to losing to those things.